WASHINGTON - The United States will not rush to war in Syria as it did in the past in the region, White House chief of staff Denis McDonough said on Sunday.

"We have to be very discerning about what's in our interest and what outcome is best for us and the prices we're willing to pay to get to that place," McDonough said on CBS's "Face the Nation" program.

"We've rushed to war in this region in the past, we're not going to do it here," he added, referring to the March 2003 invasion of Iraq by then President George W. Bush under the pretext that Baghdad had weapons of mass destruction which turned out to be false.

The Obama administration is mulling over all options on the table barring boots on the ground in its handling of the Syrian conflict, as it concluded last week that the Syrian government had used chemical weapons, including the nerve agent sarin, against the opposition forces.

President Barack Obama has called the use of chemical weapons a "red line" that would trigger deeper US involvement in the Syrian conflict. His administration has given more aid including " military support" to the rebels recently.